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IIG MICROSCOPIC FUNGI.
The under surface of the leaves of the white
Dutch clover are often sprinkled with black spots,
which are nearly round and very numerous. These
are so many clusters of fungi belonging to a
different section, in which the threads are the
important feature. But another parasite is also
found on leaves of the same plant,
in which the
distorting them and twisting
pustules are far less numerous and regular, and
are often found on the petiole as well as the leaf,
them in various directions
(plate VII. fig. 154). This is the clover rust
{Uromyces apiculataj Lev.), which is a parasite on
numerous plants, being found also on the great
water-dock and other kinds of dock. The spores
are ovoid and brown, with a short peduncle (plate
VII. fig. 155). A very beautiful species occurs on
the leaves of the ladies-mantle {Alchemilla) ,
but
hitherto we have not been fortunate enough to
collect it.
It can scarcely be too great an assumption to
too far to affirm that all who know
suppose that every one is acquainted with the goatwillow
(Salix caiyrea)f or that every schoolboy
knows the birch [Betula alha). It may be proceeding
a step
these trees weU enough to distinguish the one from
the other, will have observed the under surfaces of
the leaves of both sprinkled with a golden dust,
during the summer months, and which are the
spores of a parasitic fungus. So common is this
orange-coloured powder
on leaves of the trees